In the state of the art, high frequency modulators, also called radio frequency modulators, are known that are based on in-phase (I) and quadrature (Q) components (I/Q data), namely I/Q data of a baseband signal. In fact, these modulators are inter alia used in signal generators or communication systems for generating a signal wherein these modulators are used to generate wanted signal portions. Typically, this is done by multiplying a modulated baseband signal represented by its I/Q components with a local oscillator signal having harmonics. Thus, the outputted signal also has harmonics assigned to the frequency of the outputted signal, also called modulation output frequency. The harmonics arise from the approximately rectangular signal form of the local oscillator signal which is advantageous when multiplying the local oscillator signal with the baseband signal. Typically, the multiplication of the baseband signal with the rectangular local oscillator signal yields components like
            B      ⁡              (        t        )              *    L    ⁢                  ⁢          O      ⁡              (        t        )              =            B      ⁡              (        t        )              *          [                        sin          ⁡                      (                          w              ⁢                                                          ⁢              L              ⁢                                                          ⁢                              O                ⁡                                  (                  t                  )                                                      )                          +                              1            3                    *                      sin            ⁡                          (                              3                *                w                ⁢                                                                  ⁢                L                ⁢                                                                  ⁢                                  O                  ⁡                                      (                    t                    )                                                              )                                      +                              1            5                    *                      sin            ⁡                          (                              5                *                w                ⁢                                                                  ⁢                L                ⁢                                                                  ⁢                                  O                  ⁡                                      (                    t                    )                                                              )                                ⁢                                          ⁢          …                    ]      
In many applications, only the component B(t)*sin(wLO(t)) of the several components mentioned above is of interest so that the other components relate to disturbances which have to be filtered. Typically, analog filters are used for suppressing the disturbances, namely the unwanted components resulting from multiplication of the baseband signal with the rectangular local oscillator signal.
However, complex filters are necessary in applications that use a variable modulation output frequency since the respective filters also have to be variable in order to ensure that the filters can be adapted with respect to the modulation output frequency.
Accordingly, there is a need for a less complex and more cost-efficient possibility to suppress unwanted signal portions, in particular harmonics.